Method for prolonging service life of a machine for bending tubes

ABSTRACT

A method for prolonging service life of a machine for bending tubes comprises flame spraying a coating of less than 0.1 mm of molybdenum or molybdenum alloy to at least one surface of a fold smoothing tool.

BACKGROUND OF THE INVENTION

The present invention relates to a tool on tube or profile bending machines.

During the bending of tubes by means of tube bending machines, in which the tubes are clamped in place and bent by drawing at the free end, folds may be produced on the inside of the bend as a result of upsetting of the material. In order to avoid this, a tool, the fold smoothing tool, is used for reducing the fold formation. This shaped piece can have different designs and is occasionally designated as a fold smoothing shell or fold smoothing shoe. It supports the tube on the inside of the forming zone in the direction of the part which has just been bent. During the bending, the tube is drawn with considerable pressure force via the fold smoothing tool, thereby resulting in considerable wear on the fold smoothing tool. To avoid the wear in the fold smoothing tool, it is protected with additional materials, such as, for example, aluminum bronze, beryllium bronze or other bronze materials. Nonetheless, the fold smoothing tool is impaired to a considerable extent and therefore has to be exchanged relatively frequently. Tests with lubricants, for example molybdenum lubricant or titanium nitrite or titanium carbon nitrite, were also unable to produce any substantial prolongation in service life.

In addition, during bending, mandrels, rollers, guide aids, dies and guide rails are also required, which are likewise highly stressed and therefore also have to be exchanged, even if not so frequently.

The object of the present innovation is therefore to propose a means with which the service life of the tools on tube and profile bending machines can be prolonged.

SUMMARY OF THE INVENTION

The foregoing object is achieved according to the invention by providing a tool, such as a fold smoothing tool, mandrel or guide rails, wherein a coating of molybdenum or of a molybdenum alloy is applied to at least the surface touching the tube or profile.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: shows a mandrel bending machine for bending tubes; and

FIG. 2: shows a fold smoothing tool having a protective coating in accordance with the present invention.

DETAILED DESCRIPTION

A mandrel bending machine for bending tubes is shown in FIG. 1. Here, the bending is effected by drawing the tube 1 by means of a clamp device 2 by rotating the die 3. A rail 4 and a fold smoothing tool 5 provide for the external guidance, and the displaceable mandrel 6 arranged in the interior prevents a change in the tube diameter. Those surfaces of the rail 4, of the fold smoothing tool 5 and of the mandrel 6 which come in contact with the tube are provided with a coating of molybdenum or molybdenum alloy.

FIG. 2, by way of example, shows a fold smoothing tool 5 in which a protective coating 7 is applied to the surface 8 touching the tube.

According to the present invention, a coating of molybdenum or of a molybdenum alloy is applied to that surface of a fold smoothing tool, a mandrel, rollers, guide aids, dies or guide rails which touches the tube. This coating may be less than 0.1 mm and nonetheless produces a considerable prolongation in the service life. The molybdenum is applied to the surface by means of a flame spray process, by electroplating or by vapor deposition. 

1-2. (canceled)
 3. A method for prolonging service life of a machine for bending tubes, the method comprising flame spraying a coating of less than 0.1 mm of molybdenum or molybdenum alloy to at least one surface of a fold smoothing tool.
 4. The method of claim 3, further comprising flame spraying a coating of less than 0.1 mm of molybdenum or molybdenum alloy to at least one surface of a mandrel.
 5. The method of claim 3, further comprising flame spraying a coating of less than 0.1 mm of molybdenum or molybdenum alloy to at least one surface of one or more rollers.
 6. The method of claim 3, further comprising flame spraying a coating of less than 0.1 mm of molybdenum or molybdenum alloy to at least one surface of one or more guide aids.
 7. The method of claim 3, further comprising flame spraying a coating of less than 0.1 mm of molybdenum or molybdenum alloy to at least one surface of one or more dies.
 8. The method of claim 3, further comprising flame spraying a coating of less than 0.1 mm of molybdenum or molybdenum alloy to at least one surface of one or more guide rails.
 9. A method for prolonging service life of a machine for bending tubes, the method consisting of flame spraying a coating of less than 0.1 mm of molybdenum or molybdenum alloy to at least one surface of a fold smoothing tool.
 10. The method of claim 9, further consisting of flame spraying a coating of less than 0.1 mm of molybdenum or molybdenum alloy to at least one surface of a mandrel.
 11. The method of claim 9, further consisting of flame spraying a coating of less than 0.1 mm of molybdenum or molybdenum alloy to at least one surface of one or more rollers.
 12. The method of claim 9, further consisting of flame spraying a coating of less than 0.1 mm of molybdenum or molybdenum alloy to at least one surface of one or more guide aids.
 13. The method of claim 9, further consisting of flame spraying a coating of less than 0.1 mm of molybdenum or molybdenum alloy to at least one surface of one or more dies.
 14. The method of claim 9, further consisting of flame spraying a coating of less than 0.1 mm of molybdenum or molybdenum alloy to at least one surface of one or more guide rails.
 15. A method for prolonging service life of a machine for bending tubes, the method comprising electroplating or vapor depositing a coating of less than 0.1 mm of molybdenum or molybdenum alloy to at least one surface of a fold smoothing tool.
 16. The method of claim 15, further comprising electroplating or vapor depositing a coating of less than 0.1 mm of molybdenum or molybdenum alloy to at least one surface of a mandrel.
 17. The method of claim 15, further comprising electroplating or vapor depositing a coating of less than 0.1 mm of molybdenum or molybdenum alloy to at least one surface of one or more rollers.
 18. The method of claim 15, further comprising electroplating or vapor depositing a coating of less than 0.1 mm of molybdenum or molybdenum alloy to at least one surface of one or more guide aids.
 19. The method of claim 15, further comprising electroplating or vapor depositing a coating of less than 0.1 mm of molybdenum or molybdenum alloy to at least one surface of one or more dies.
 20. The method of claim 15, further comprising electroplating or vapor depositing a coating of less than 0.1 mm of molybdenum or molybdenum alloy to at least one surface of one or more guide rails. 